There have been semiconductor devices with semiconductor chips stacked in multiple stages, thus allowing a reduction in footprint. Such semiconductor devices are manufactured by bonding, in multiple stages, substrates in which semiconductor elements or integrated circuits are formed, and dicing them into semiconductor chips, for example.
A semiconductor oxide film is generally provided on a surface of each substrate to be bonded, and a plurality of electrodes to be connected by bonding substrates is provided in corresponding positions in a surface of each semiconductor oxide film. Here, in a step of bonding substrates to each other, misalignment in position of electrodes to be connected may be produced.
In such a case, metal of an electrode provided in one substrate directly contacts a semiconductor oxide film provided on a surface of another substrate, and is diffused into the other substrate in a heat treatment step performed later, adversely affecting the characteristics of a semiconductor element or an integrated circuit provided in the other substrate.